Brown scum at water line after purge

[joecooler]

I've had my spa for 2.5 years now, on my 5th fill. Each fill seems to bring some new mystery. The first fill was kind of a mess, I found TFP and cleaned it w/ahh-some, and switched to an SWG. Have had relatively few issues since then. A couple of weeks ago it was time to purge and refill again, did the usual ahh-some clean w/minimal results - just some small flecks of brown/green on the foam and a little bit on the walls of the tub once the jets stopped running. Did a thorough rinse after emptying the tub, and refilled. Since then, for the first time, I've been seeing a pretty rapid build of of brown scum at the water line. The build up is decreasing but I am confused how this could happen with a fresh fill, especially when it never happened before. I also developed a mild rash and I felt like my skin was maybe a bit prickly after using the tub, something else I haven't noticed before (this could also just be me being hypersensitive!). Aside from this the water is perfect - very clear, all chem levels good. If anything the Cl has been a bit on the high side. I can only think of two possible sources for the scum:

1. I didn't replace the filters, did use filters that had been rinsed, cleaned w/eco soak, and dried. Maybe these weren't clearing the water properly, or actually added some gunk to it. I replaced these w/new filters yesterday so if the scum doesn't come back I'm gonna assume the filters were part of the issue.
2. There was still gunk in the lines of the spa when I refilled it. I've always wondered about how to clean the lines w/out doing a full refill and dump after using ahh-some - something I'd rather avoid for time and cost reasons. How can I tell if this is the source of my problems? After doing an ahh-some purge, do people do another full fill and dump to really get the pipes cleaned out? Seems like a lot of work but maybe it's needed.

Any other thoughts or suggestions are appreciated - I'd like to figure this one out so it doesn't happen again!

 

[Mdragger88]

What you are seeing is residual being flushed from the lines. Just wipe it w/ a microfiber rag & get it out of there.
I had this issue when i only did 1 purge after an extended period between water changes. A second purge remedied my situation.
Now I always go to shock level, dose w/ Ahhsome, let it run & scoop foam/wipe until it dissapates then let it rest 30 minutes or an hour. Then I add a 1/2 dose & let it run again. Many times this has produced a fair amount of gunk even though the first purge was pretty uneventful.
Not sure how your tub is made but some are able to fill partially (above the intake) , have the hose filling in the filter area & “bump” the pump (so water comes out of the jets) to flush the lines w/ fresh water so its not another complete drain. If you have any high level intakes this will not help u save much water. I have never done this as i am a scaredy-cat.
I just did my purge/refill yesterday & when rinsing with the hose i just force the water into all the jets & it runs back out. Then i use a small aquarium/fountain pump & microfiber rags to get the last little bit of water out before refilling. I don’t refill & dump.
The makers of Ahhsome do also have a product called Serum that is a weekly enzyme addition to reduce biofilms - it’s not really recommended to take the place of the regular water exchange/ purge process though it may help you extend intervals.

 

[Mdragger88]

Also if u do the dichlor then bleach method & your cya is really low/fc high the itchy stuff could be irritation from that. When my cya gets low but I’m chlorinating like its not my husband gets a rash. We get alot of splash out so I have to keep an eye on my cya.

 

[joecooler]

What you are seeing is residual being flushed from the lines. Just wipe it w/ a microfiber rag & get it out of there.
I had this issue when i only did 1 purge after an extended period between water changes. A second purge remedied my situation.
Now I always go to shock level, dose w/ Ahhsome, let it run & scoop foam/wipe until it dissapates then let it rest 30 minutes or an hour. Then I add a 1/2 dose & let it run again. Many times this has produced a fair amount of gunk even though the first purge was pretty uneventful.
Not sure how your tub is made but some are able to fill partially (above the intake) , have the hose filling in the filter area & “bump” the pump (so water comes out of the jets) to flush the lines w/ fresh water so its not another complete drain. If you have any high level intakes this will not help u save much water. I have never done this as i am a scaredy-cat.
I just did my purge/refill yesterday & when rinsing with the hose i just force the water into all the jets & it runs back out. Then i use a small aquarium/fountain pump & microfiber rags to get the last little bit of water out before refilling. I don’t refill & dump.
The makers of Ahhsome do also have a product called Serum that is a weekly enzyme addition to reduce biofilms - it’s not really recommended to take the place of the regular water exchange/ purge process though it may help you extend intervals.

Thanks, lots of good stuff there! I have been cleaning it out as it forms and it's decreasing a lot so that's a good sign.
I also clean out the foam as it forms ... kind of a pain but seems worth doing to get the gunk out of the water.
Sadly I can't do a half-fill and flush ... until the jets are ALL under the water, running them just creates a water fountain spraying the side of my house etc. Kind of a mess. I may try your second dose concept, I'm also somewhat inclined to do a second fill and purge next time just to see what happens.
Bottom line it sounds like I shouldn't be too surprised or alarmed so that's good news!